Enhancing the prestige of a mechanical timepiece mechanism, more specifically a watch, with regard to clients, is often achieved by revealing its components, and skeleton movements are appreciated by clients who can view the important functions of the complex object in their possession. The presentation of the tourbillon in high end timepieces, or of the balance spring in more conventional timepieces, which form the visible heart of a movement, are particularly valued. The best display possible therefore constitutes an important asset and a decision criteria for the purchaser. Thus it is useful to render the balance spring as visible as possible, and at any time of the day or night, and in particular by making it luminous.
Users often feel the need to verify the proper operation of their watch or of their timepiece, which can be achieved by listening to the ticking of the mechanism. However, this method is not possible in a noisy environment, or for the hard of hearing.
CH Patent Application No 699780A2 in the name of RICHEMONT discloses a self-compensating silicon watch spring, with a coating covering one portion of the outer surface of the spring.
EP Patent Application No 1605182A1 in the name of CSEM discloses a temperature compensated sprung balance with a quartz spring, and particularly a quartz substrate, the cut of which is chosen to thermally compensate the deviations of the balance spring and those of the balance.
EP Patent Application No 2407831A1 in the name of ROLEX discloses a silicon, diamond or quartz balance spring which includes pierced holes distributed over the length thereof and alternating with bridges.
EP Patent Application No 1791039A1 in the name of SWATCH GROUP RESEARCH AND DEVELOPMENT discloses a balance spring made of athermal glass from photo-structurable glass by UV radiation.
WO Patent Application No 2008/080570A2 in the name of COMPLITIME discloses a balance spring and a balance made from the same material, particularly diamond, quartz or ceramic.